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Discussion Starter · #1 ·
After reviewing hundreds of posts and a number of different websites, I want to comment on the process of removing a frozen oxygen sensor on a 2001 Sequoia (4X4).
The oxygen sensor was Bank 2 sensor 1 (passenger side, pre-cat). I found it to be hopelessly frozen into the manifold - I used WD40, PB Blaster and several other 'rust-busting' oils to no avail. I tried the Kano labs super penetrant oil and this was the best of the lot, but still the O2 sensor needed a 22mm socket and a pipe wrench with a cheater bar to budge.

In this process, the threads stripped. I then tried to use a 16mm tap reamer to open the threads, but the reamer was 'loose'. I tried with steel picks to open the threads, but it was not possible. Access to this sensor is difficult, as you have to come up from beneath the vehicle - it is a tight fit and you can barely fit two hands into the space.

I finally gave up and began to cost it out. The Toyota dealership wanted $1100 to do the job - a new manifold for $400 and labor at $700. I called an independent Toyota repair mechanic who did it for $160. The O2 manifold port just needed to have the threads opened up with a reamer and it didn't even need a permicoil insert.

I asked the mechanic how they removed frozen O2 sensors; he said that in many cases, they are impossible to remove without thread stripping. The heat causes the metals to bond to each other and metal disintegration occurs when moved. He further said the driver's side pre-cat O2 sensor is even more difficult to get at - needless to say, I will definitely farm that job out if it even comes to it.

This was one of the more frustrating driveway jobs that I've ever attempted. If I were to advise someone about it - I'd say farm it out. Otherwise, find a way to soak the sensor base in the Kano oil for about 24 hours before putting a socket to it. I had to chop off the wires to get a regular 22mm socket onto it, thus destroying the sensor - therefore be sure this is your problem (dealer sensor $180). The open-side specialty O2 socket began to slip on the O2 sensor base and round it off - a rounded off base would be a real removal nightmare, as access is very tight, as aforementioned.

The 2001 Toyota Sequoia Bank 2 sensor 1- O2 sensor base has 18mm threads with a pitch of 1.5 - this information was hard to find and erroneously stated in some websites. It is not 16mm, as told to me by a Toyota dealer parts technician.

I discovered I was closer to a fix than I had imagined. The manifold threads were not stripped; it was metalic deposits left behind by the deteriorating O2 sensor, giving the visual impression of stripped threads. The proper reamer size was 18mm; when carefully run thru the manifold threads, they cleaned up enough to seat and torque the new O2 sensor to specs.

I will never patronize the Toyota service department again - I consider them unethical; in addition, you cannot trust the information that the Toyota dealer parts department provides. The non-dealer mechanic explained it thus - they (Toyota counter parts people) aren't mechanics - they're inventory jockies; thus they have limited knowledge.
I recommend the Kano labs lubricants for loosening stuck parts - far superior to anything you can purchase off the shelfs at most car parts places.

Good luck - you'll need it.
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